A rifled slug has rifling built into the slug itself. This makes up for the barrel not having rifling. The slug spins in a motion similar to what rifling would cause due to the air passing over the grooves on the slug. Rifled slugs shot from a smooth bore are relatively accurate out to about 50-75 yards.
Sabot slugs are a smooth slug (similar to a rifle bullet) fired from a plastic housing. This housing reacts to rifled barrels, and causes the slug to spin. Because it's making contact with actual rifling, it will spin much faster than a rifled slug fired from a smooth barrel. The result is a slug that is more accurate, out to about 100-150 yards rather than 50-75 yards.
If you were to fire a sabot slug from your smooth bore Mossberg 500, you would create an effect similar to firing a mini ball from a smooth bore musket. Your shot pattern with 5 shots at 50 yards would probably be about 1 to 2 feet. Not great grouping.
The slug itself has spiral veins on it's outside with a solid base. When the slug goes out the barrel and down range the wind resistance against the veins will impart a certain amount of spin to the slug. Theoretically stabilizing the slug and improving accuracy. Same principle as a pin wheel. Wind makes it spin.
You can also get a rifled choke tube. Not sure how well they work. I would assume that it is best to either buy the rifled slugs or use sabot rounds through rifled choke tubes. You can also buy a slug barrel for your mossberg. Should cost around 150 to 175. Not cheap but that would give you better sights and better accuracy.
"As senior rooster ’round here, it’s my duty, and my pleasure, to instruct junior roosters in the ancient art of roostery” Foghorn Leghorn
Don't most manufacturers recommend improved choke. They do if i remember right.
I can't see why they would. An IC choke constricts the barrel slightly (0.01 inches). I'm thinking that they might say you should use an IC choke or smaller constriction, meaning only use Cylinder, Skeet, or Improved Cylinder chokes.
Also, here are the best rifled slugs (in my opinion):
They tested 'rifled slugs and they don't spin.The best barrel they have found for foster type slugs is a backbored bbl that is bored to .740".Actually they are using this for shot too as it distorts shot less.The standard cylinder bore is .729" and works well with foster type slugs.They can be fired in any choke including full 'but' they create a pressure surge going through the choke and put more trauma on the slug as it exits the barrel.When gasses escape past any projectile in any firearm they pass the projectile.If they do this unevenly it pushes the projectile slightly one way or another causing it to be slightly unstable.With rifled barrels they straighten up because they are spinning.But a foster type slug with no spin stays 'yawed' causing inaccuracy.Actually they do straighten a little once they are free of the turbulance of the gasses because of the 'skirt on the slug. The pressure surge lets higher pressures effect the slug so the less choke the less pressure and the less effect on the slug.Sabots wont work in smoothbores but often foster type slugs work well in rifled barrels,especially the ones that the wadding stays attached.I have gotten fair accuracy from any decent slug but prefer Remington,Winchester,and federal,in that order. sam.
Hey Righteous ! I didn't know that, though I own a Mossberg with ported barrel I don't intend to shoot slugs through it Thanks for the Heads up !
Though I beleive you I've not read this anywhere before and I go to Mossbergs web site daily.
The only reason that you shouldn't fire slugs from a ported barrel is because the slug can shave off lead as it goes through the ports, and potentially damage them overtime. But shotguns with ported barrels will fire slugs.
A.H., if you were ever put in the situation where you needed to fire a slug, I would say that you wouldn't have a problem.
I solve this dilemma by shooting shot out of my smootbore
tube and slugs out of my rifled tube. I feel it a great asset to
have this choice of specialization. You get the best performance
from either shot or slug.
Although it has a supposed benefit there is little, if any, gain from
shooting a slug with rifling on the exterior through a smooth
bore shotgun tube.